Method of tipping aircraft propellers



F. W. CALDWELL ET AL METHOD OF TIPPI NG AIRCRAFT PROPELLER S Filed Oct. 11. 1921 ll atented Apr. 15, 1924.

ENK W. CALDWELL AND JOHN (2. MORSE, 0F DAYTON, OHIO.

METHOD OF TIPPING- AIRCRAFT PROPELLERS.

Application filed. October 11, 921. Serial to. 506,983.

To all whom it may concern:

Be it. known that we, FRANK W. CALD- WELL and JOHN C. MORSE, citizens of the United States, residing at Dayton, in the county of Montgomery and State of Ohio, have invented certain new and useful Improvements in Methods of Tipping Aircraft ropellers, of which the following is a specification.

' Our invention relates to an improved protective covering or tipping for propeller blades and the edges and tips thereof.

Considerable difiiculty has been experienced with the boot type of tipping hereto fore used as a protective covering for airplane propellers wing to the cracking and breaking of the metal composing the same, with the result that parts of the covering or the whol boot-like tipping has been thrown off the propeller.

Our invention aims to overcome this difiiculty by providing a sheathing or tipping formed from a continuous sheet of metal fabric or other suitable material which is applied to the tip, and along the leading edge of the blade and supplemented at the tip by a small piece of like material. The covering or tipping is cut from a sheet of suitable material, preferably metal, which is then notched on opposite sides so as to form a narrow, continuous central strip having a lurality of spaced segments extending laterally therefrom, and a plain portion at one end adapted to partially embrace the tip of the blade. 1

In applying the tipping to a propeller blade the central strip is bent over the leading edge and the segments contact with and follow the contour of opposite faces of the blade. Each segment is firmly secured to the blade so that even a crack extending through the central strip between opposite notches would do no harm. In fact, should one of the small sections formed by several of such cracks happen to fly 03, it would not greatly unbalance'the propeller.

Furthermore this improved protective covering, because of its flexibility, does not in any way restrain the movements of the propeller.

The invention is described in the following specification in connection with the acc'ompanying' drawings, in which:

Figure 1 is a plan view of the tipping as cut from the sheet metal and notched.

should be balanced befor enamelling 1 Figure 2 is aplan view of the small sup-s 'plemental end piece.

Figure 3 shows the manner in which the tipping is applied to a propeller blade.-

Figure 4 is a side elevation of a propeller blade having our improved tipping applied thereto.

As shown in Figure 1, the tipping is cut from a metallic, strip so as to form'an end piece 10 adapted to extend across one face, and have its edges bent over the edges of the blade 11, at the tip thereof. The body of the sheathing is notched on opposite s1des, as shown at 12, in order to form a series of spaced segments or projections 13 which may be of curved irregular, or polygonal form as desired. ese segments 13 extend from opposite sides of a central continuous strip 14 which is integral with the end piece 10 and projects therefrom at one side of the longitudinal axis Bf the latter.

The tipping is applied to a propeller blade in such manner that the continuous strip 14; is bent over the leading edge and the segments 13 contact with opposite faces of the blade. In Figure 2, a small end piece 15 is illustrated whichis adapted to be applied at the tip of the blade across the face opposite. from the end piece 10. The edges 16 of the end piece 10 are bent over the ed es and tip of the blade and overlap the small piece 15. In order not to have a ridge where the metal is thus overlapped} the metal should befiled to a knifeedge along the edge of the under pieceas well as along the edge of the overlapping piece. The end pieces are preferably secured to the propeller blades by means of rivets 17 so as to form a sort of a cap for receiving the tip of the propeller. lhe segments 13 are bent to conform to the contour of the blades and are secured there-. to by means of screws 18.

The screw and rivet heads as well as the seam of the cap are subsequently covered with solder. The solder is then cleaned ofi level with the metal of the sheathing so as to present a smooth exterior. Several small holes 20, usually three in number, are drilled through the tipping at the extreme tip 19 to allow any moisture that may be forced under the tippin to escape under the influence of centri ugal force. The propeller but if the ti ping has been carefully app ed the prope ler is usually nearly in balance.

Having thus described our invention, we

claim:

1. The combination with a propeller blade, of tipping therefor comprising a continuous strip embracing an edge of the blade, and spaced segments extending from opposit sides of said strip adapted to be secured to said blade.

2. The combination with a propeller blade, of tipping therefor comprising a continuous sheet of material having a series of notches therein forming a plurality of laterally projecting spaced segments.

3. The combination with a propeller blade. of tipping therefor comprising a sheet of material having an end piece adapted to be secured at the tip of the propeller, a 'continuous strip extending from said end piece and adapted to be bent over the leading edge of the blade,"and spaced segments projecting iaterally from said strip.

4. The combination" with a propeller blade, of tipping therefor comprising a sheet of material having an end piece adapted to partially embrace the tip of the pro-v peller, a. continuous strip extending from said end-piece and adapted to be bent over' the leading edge of the blade,means for securingsaid strip to the blade, a supplemental end piece for forming with said first 1 brace an edge of the blade, and spaced segments projecting from said strip bendable to conform to the contour of the faces of said blade.

6. A tipping for propeller blades comprising a sheet of material having a series of notches cut therein for 'forming a row of spaced segments.

7. A tipping for propeller ing a sheet of material haying a continuous strip, and a plurality of spaced segments projecting laterally there-from.

8. A tipping for propeller blades comprising a sheet of material having a continuous strip, a plurality of spaced segments projecting laterally from said strip, and an end piece integral with said strip adapted to engage the tip of the propeller blade.

9. A tipping for a propeller blade comprising an end cap for receiving the tip of the blade, a strip extending from said cap, and a plurality of spaced segments projectinp; laterally from said strip.

In testimony whereof we hax e affixed our signatures.

FRANK WA CALDWELL. JOHN C. MORSE.

blades compris- 

